Work Step by Step
Carlos started his homework 12 minutes early. In 60 minutes, he can get 25 problems done, so in 12 minutes, he can get 5 problems done. This expression represents how many problems he gets down after $x$ hours from when Cecelia started her homework $25x + 5$ Cecelia had no head-start and can do 30 problems an hour. This expression represents how many problems Cecelia did $x$ hours from when Cecelia started her homework $30x$ Equate them and solve $25x+5 = 30x$ $5 =5x$ $x = 1$ The question is asking how long after Carlos started would they have the same number of problems done. Carlos started $0.2$ hours early, so the answer is $1 + 0.2$ or just $1.2$ hours.